The role of thoracic paravertebral block (PVB) in preventing chronic postsurgical pain (CPSP) after breast cancer surgery (BCS) has gained interest, but existing evidence is conflicting, and its methodological quality is unclear. This meta-analysis evaluates efficacy of PVB, compared with Control group, in preventing CPSP after BCS, in light of the Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT) recommendations. Electronic databases were searched for randomized trials comparing PVB with Control group for CPSP prevention after BCS. Eligible trials were assessed for adherence to IMMPACT recommendations. The primary outcomes were CPSP at 3 and 6 months, whereas secondary outcomes were PVB-related complications. Data were pooled and analyzed using random-effects modelling. Trial sequential analysis was used to evaluate evidence conclusiveness. Data from 9 studies (604 patients) were analyzed. The median (range) of IMMPACT recommendations met in these trials was 9 (5, 15) of 21. Paravertebral block was not different from Control group in preventing CPSP at 3 months, but was protective at 6 months, with relative risk reduction (95% confidence interval) of 54% (0.24-0.88) (P = 0.02). Meta-regression suggested that the relative risk of CPSP was lower when single-injection (R2 = 1.00, P < 0.001) and multilevel (R2 = 0.71, P = 0.01) PVB were used. Trial sequential analysis revealed that 6-month analysis was underpowered by at least 312 patients. Evidence quality was moderate according to the GRADE system. Evidence suggests that multilevel single-injection PVB may be protective against CPSP at 6 months after BCS, but methodological limitations are present. Larger trials observing IMMPACT recommendations are needed to confirm this treatment effect and its magnitude.
aDepartment of Anesthesia, Wexner Medical Center, The Ohio State University, Columbus, OH, United States
bDepartment of Anesthesia, Vanderbilt University Medical Centre, Nashville, TN, United States
cDepartment of Anaesthesiology and Pain Medicine, University of Ottawa, Ottawa, ON, Canada
dThe Ottawa Hospital Research Institute, University of Ottawa, Ottawa, ON, Canada
eDepartment of Anesthesiology and Perioperative Medicine, Queen's University, Kingston, ON, Canada
fUniversity of Florida, Gainesville, FL, United States
gDepartment of Anaesthesia, University of Toronto, ON, Canada
hDepartment of Anesthesia and Pain Management, Toronto General Hospital, ON, Canada
iDepartment of Psychology, York University, ON, Canada
jApplied Health Research Centre, St. Michael's Hospital, University of Toronto, ON, Canada
kInstitute of Primary Health Care, University of Bern, Bern, Switzerland
lInstitute of Health Policy, Management, and Evaluation, University of Toronto, ON, Canada
mDepartment of Medicine, St. Michael's Hospital, University of Toronto, ON, Canada
nThe Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, ON, Canada
Corresponding author. Address: Department of Anesthesiology and Pain Medicine, Ottawa Hospital Research Institute, University of Ottawa, The Ottawa Hospital General Campus, 501 Smyth Rd, Ottawa, ON K1H 8L6, Canada. Tel.: (416) 278-5683. E-mail address: FAbdallah@toh.ca (F.W. Abdallah).
Sponsorships or competing interests that may be relevant to content are disclosed at the end of this article.
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Received April 09, 2018
Received in revised form May 16, 2018
Accepted May 18, 2018